Ice cream pump

ABSTRACT

A double acting pump is provided for pumping air in one cylinder and liquid mix into another. The cylinders and valve housings, together with the inlet and outlet fittings, are readily separable for cleaning. The entire pump unit may be disassembled for cleaning by the removal of four knobs or nuts.

United States Patent Berglund et al.

[ ICE CREAM PUMP [72] Inventors: Harold A. Berglund, Afton; David F.Thomas, West St. Paul, both of Minn.

[73] Assignee: Waterous Company, St. Paul, Minn.

[22] Filed: Aug. 6, 1970 211 App]. No.: 61,658

[52] US. Cl ..4l7/360, 417/415 [51] Int. Cl ..F04b 17/00, F04b 35/00,F04b 35/04 [58] Field of Search ..417/360, 415

[56] References Cited UNITED STATES PATENTS 2,005,573 6/1935 Drysdale..4 l7/4l X 2,853,226 9/1958 Maniscalco, Sr. .....4l7/4l5X FOREIGNPATENTS OR APPLICATIONS 1,267,797 l/ 1960 France ..4l7/415 PrimaryExaminer-Robert M. Walker Attorney-Robert M. Dunning ABSTRACT A doubleacting pump is provided for pumping air in one cylinder and liquid mixinto another. The cylinders and valve housings, together with the inletand outlet fittings, are readily separable for cleaning. The entire pumpunit may be disassembled for cleaning by em xal ifgur knobs .0! 1 9B-PMENTEDHBI 10 m2 SHEET 3 [IF 3 INVENTOR HAROLD BERGLUND DAV/D F7710/14/18 BY k p nmwq ATTORNEY ICE CREAM PUMP This invention relates toan improvement in the ICE CREAM PUMP and deals particularly with a pumpcapable of pumping air and a liquid mix, and combining the air with themix in a desired ratio.

BACKGROUND OF THE INVENTION In the mechanical production of ice cream,sherbert, ice milk, frozen custards and other frozen dessert products, aliquid mix is normally combined with a nontoxic gas such as air,nitrogen, nitrous oxide, or freon in order to produce a tasteful,palatable and profitable end product. The mixture is directed to asuitable freezer in which the mixture is frozen, and from which thefrozen mixture may be dispensed. The liquid mix and air are supplied tothe freezing chamber as the frozen product is dispensed, and theoperation is normally automatically controlled. The product in thefreezing chamber is maintained under pressure. As the frozen product isdispensed, the pressure drops and the pump mechanism is actuated to pumpmore of the mixture of liquid mix and air to the freezing compartmentuntil the desired pressure is attained.

One of the difficulties experienced with previous pumping equipment liesin the fact that it is difficult to maintain the apparatus in a cleanand sanitary condition. The equipmentmust be thoroughly cleaned fromtime to time to prevent the growthof bacteria. If the pump mechanism isdifficult to disassemble and clean, there is a tendency for the operatorto delay the cleaning operation and to clean the apparatus at lessfrequent intervals. One of the areas most difficult to clean oftencomprises the pressure control valve, the diaphragm of which is usuallycontacted by the mixture of air and liquid mix. This area is usuallydifficult and time consuming to clean, it is, therefore, of utmostimportance that the apparatus be easy to take apart and put together sothat it may be cleaned at proper intervals by relatively unskilledpersonnel.

SUMMARY OF THE INVENTION An object of the present invention resides inthe provision of a double acting pump including a pair of opposedcylinders, and a pair of pistons mounted at opposite ends of a pistonbar reciprocated by an eccentric carn roller rotating about an axis ofrotation. As the piston reciprocates in one direction, liquid mix is.forced from one cylinder to a mixing chamber where it is combined withair. Simultaneously, air is drawn into the opposite cylinder. As thepiston rod is reciprocated in the opposite direction, air is forcedunder pressure from the opposite cylinder, and liquid mix is drawn intothe first cylinder. The air under pressure from the opposite cylinder ismixed with the liquid mix in the mixing chamber and forced into thefreezer unit.

An important feature of the present invention lies in the simplicity ofconstruction. The device includes a motor mounted upon a base and towhich is secured the base panel of a generally U-shaped pump framehaving parallel sides. A cam follower crank is mounted upon the motorshaft and supports an eccentric bearing.

Cylinders extend in opposed relation through the paralwhich theeccentric bearing is engaged. Rotation of the motor accordinglyreciprocates the pistons in the opposed cylinders.

A feature of the present invention resides in the provision of cylinderscombined with integrally connected valve housings. The valve housingsare arranged on parallel vertical axes and are closed at their lowerends by inlet fittings. The valve chambers are provided with suitableoutlet fittings at their upper ends. The side plates of the pump frameare provided with vertically spaced yokes between which the valvechambers with the inlet and outlet fittings telescoped therein arereceived. These yokes hold the valve chambers in vertical position, andhold the inlet and outlet fittings assembled to the valve chambers. Thecylinders extend through aligned apertures in the sides of the pumpframe, and each cylinder, together with the integral valve chambers andthe inlet and outlet fittings are held in place by a pair of knobs ornuts threaded on studs projecting outwardly from the sides of the pumpframe on opposite sides of the cylinder apertures. By removal of theseknobs, the entire assembly may be removed and completely disassembledfor cleaning.

A further feature of the present invention resides in a provision of asimple check valve arrangement controlling the flow into and out of thevalve chamber. Each check valve comprises a valve body verticallyslidable in the valve chamber and having a tapered lower end which iscircumferentially grooved to accommodate an O-ring. This sealing ringseats against either a portion of the valve chamber or the inlet fittingto form a seal. The valve bodies are preferably rectangular in sectionso that the liquid or air may flow freely about the valve when it isopen. The valve bodies are made of stainless steel or other relativelyheavy material so as to seat by gravity, eliminating the necessity ofsprings.

A further feature of the present invention resides in the provisionv ofa pressure actuated control switch which is connected to the outletfitting of a valve chamber connected to the air cylinder. As a result,the switch diaphragm communicates only with the air and accordingly doesnot come into contact with the liquid mix, eliminating the necessity ofcleaning the switch diaphragm.

A further feature resides in the provision of a means for readilydetaching the encircling sealing ring from each piston. A finger notchis provided communicating with the peripheral groove to facilitateremoval of the sealing ring.

These and other objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view ofthe pump in readiness for operation.

FIG. 2 is a top plan view of the assembled pump.

FIG. 3 is a horizontal sectional view through the motor axis showing theportions of the piston bar or rod and one of the pistons.

FIG. 4 is a vertical sectional view through the pump, the position ofthe section being indicated by the line 4-4 of FIG. 2.

FIG. 5 is a sectional view through one of the check valves, the positionof the section being indicated by the line 5-5 ofFlG. 4.

FIG. 6 is a perspective view of one of the cylinder and valve chamberunits.

FIG. 7 is a sectional detail through the piston rod looking toward oneof the pistons, the position of the section being indicated by the line7-7 of FIG. 2.

FIG. 8 is a perspective view of the piston rod.

FIG. 9 is a perspective view of one side of the pump frame.

FIG. 10 is a perspective view of one of the check valves with thesealing ring removed.

FIG. 11 is a perspective view of the end of one of the pistons, showingthe notch employed to simplify the removal of the sealing ring from thepiston.

DESCRIPTION OF THE PREFERRED FORM OF CONSTRUCTION The pump is indicatedin general by the letter A. The pump includes a motor 10 which ismounted upon a supporting base 11. The motor 10 is provided with aflange to which is secured a mounting plate 13. A pump frame indicatedin general by the numeral 14 is bolted or otherwise secured to theflange 12 and plate 13 by bolts 15. The pump frame 14 includes a baseplate 16 which supports a pair of forwardly projecting parallel framesides 17. A pair of generally triangular upper reinforcing ribs 19 and asimilarly shaped lower pair of reinforcing ribs 20 are provided tostrengthen the pump frame. A cylindrical crank 21 is mounted on theshaft 22 of the motor 10 and supports an eccentric bearing 23. Theeccentric bearing 23 is designed to reciprocate the piston rod 24 whichwill be later described in detail.

A cylinder and a valve housing unit indicated by the numeral 25 issupported upon each pump frame side 17. As indicated in FIG. 6 of thedrawings, each unit 25 includes a cylinder 26 having an open inner endand having a flange 27 at its opposite end. Spaced pairs of cars 29extend outwardly from diametrically opposite sides of the flange 27, theears 29 being spaced to provide grooves 30 therebetween designed toaccommodate mounting studs on the sides 17 of the frame 14. Integralwith the flange 27 is a valve housing member 31 including a relativelysmall diameter central portion 32, to which is connected an upper largerdiameter portion 33 and a lower larger diameter portion 34. An uppercylindrical sleeve 35 forms an extension of the upper chamber portion33, and a lower sleeve portion 36 forms a downward extension of thevalve chamber portion 34. The entire unit 25 may be cast of plastic orother suitable material which can be readily cleaned and sterilized.

With reference to FIG. 4 of the drawings, it will be noted that anopening 37 is provided between the small diameter center portion 32 ofthe valve chamber 31 and the interior of the cylinder 26. As shown inthis figure, the frusto-conical connecting portion 39 of the housingbetween the small diameter portion 32 and the upper larger diameterportion 33 forms a seat for a check valve 40. The frusto-conical portion41 between the small diameter portion 32 and the larger diameter lowerportion 34 of the valve chamber forms a stop to limit upward movement ofan inlet check valve 42. In the same manner, the smaller diameterportion 32A of the valve housing at the right of FIG. 4 is provided withan opening 37A communicating with the interior of the cylinder 26A, andthe frusto-conical portion 39A connecting the small diameter portion 32Awith the larger diameter upper portion 33A forms a seat for a checkvalve 43. The frusto-conical connecting portion 41A acts to limit upwardmovement of the check valve 44.

The air inlet fitting 45 and the mix inlet fitting 46 are of generallyidentical form and similar identifying numbers will be used. Thefittings 45 and 46 include a cylindrical sleeve 47 which fits within thelarger diameter housing portion 34A, and substantially frusto-conicalconnecting portion 49 connects the sleeve 47 with a smaller diametersleeve 50. A sealing ring 51 encircles the base of the sleeve 47 andfits between the outer periphery of the frusto-conical portion 49 andthe base of the housing sleeve 36. The check valve 44 is designed toseat against the frusto-conical portion in closed position of thisvalve. The air inlet fitting additionally includes holes 48 in the wallhereof. The holes 48 prevent malfunction of the pump in the event theliquid mix supply hose is accidentally attached to the air inlet fittingby bleeding air into the fitting above the hose connection.

The check valves 40, 42, 43, and 44 are all identical and areconstructed as best illustrated in FIG. 10 of the drawings. The valve isprovided with a generally rectangular body portion 52 having slightlyrounded comers as indicated at 53 which fit in the enclosing wall in themanner illustrated in FIG. 5 of the drawings. The rectangular body 52 isprovided with a slightly tapering lower end 54 which terminates in asubstantially cylindrical downward projection 55 having a peripheralgroove 56 extending thereabout. The groove 56 is designed to accommodatea sealing ring 57 which may be of substantially circular cross section,and which forms the actual seal. The valve bodies 53 are preferably madeof stainless steel or other relatively heavy materials so that thevalves may seat by gravity. The flat sides of the body permit the flowof air or fluid about the valve body when the valve is in open position.

An air outlet fitting 59 closes the top of the valve chamber 31A orvalve chamber housing as indicated in FIG. 4. The upper fitting 59includes a ring shaped closure member 60 having a depending peripheralskirt including a larger diameter portion 61 and a smaller diameterlower portion 62. The skirt portion 61, 62, is designed to telescopeinto the upper end of the sleeve 35A and into a groove 63 in the innerwall surface of the valve chamber slightly beneath the sleeve 35A. Anintegral tube 64 extends upwardly from the ring shaped plate 60 and isdesigned to accommodate the end of a hose 65 (see FIG. 1). The upperfitting 59 is actually a T connector having a branch 66 adapted toaccommodate the end of a second hose 67 leading to the pressure actuatedswitch.

The outlet fitting 69 forming an extension of the upper end of the valvehousing 31 on the left side of FIG. 4 includes a slightly tapered ringshaped upper closure 70 designed to extend into the upwardly extendingsleeve 35 on the valve housing, and a depending skirt portion 71 whichfits into a cavity 72 inwardly of the sleeve 35, the fitting 69 andvalve housing being sealed by a sealing ring 73. The fitting 69 is a Tconnector having an outlet sleeve 74 extending laterally and an airinlet sleeve 75 extending upwardly therefrom. The upper end of the airinlet sleeve 75 is a relatively small diameter while the lower portionthereof is of a larger diameter as indicated at 76. This provides avalve seat 77 between the portions different diameter. A check valve 79which is preferably of generally square cross section includes anupwardly projecting grooved end 80 which accommodates a sealing ring 81designed to form the seal between the valve 79 and the upper portion ofthe air intake sleeve 75. The valve 79 is urged upwardly by a spring 82which may rest upon the upper surface of the check valve 40 or may beotherwise supported within the outlet fitting. The valve 79 differs fromthe previously described check valves in that this valve may be made ofplastic or other relatively light weight materials in view of the factthat it must be forced upwardly in closed position by the spring. Theflexible tube 65 shown in FIG. 1 is connected to the air inlet sleeve 75so that air forced from the right hand piston in FIG. 4 is directed tothe top of the outlet fitting 69. I

With reference now to FIGS. 6 and 9 of the drawings, the manner ofsecuring the pistons, valve housings, and inlet and outlet fittings inplace is indicated. The outer surface of each side 17 of the'pump frame14 is provided with a generally circular ring shaped area 85 encirclingan aperture 86 of proper size to accommodate a cylinder such as 26extending therethrough. Studs 87 are anchored in the side 17 ondiametrically opposite sides of the aperture 86, and extend through theslots 30 between the laterally projecting cars 29 on the peripheralflange 27 encircling the cylinder. Threaded knobs 89 may be threadedonto the studs 87 to hold the cylinder and valve housing units in place.An upper bifurcated yoke 90 projects outwardly from the side 17 abovethe ring shaped faced area 85, and a lower bifurcated yoke 91 projectsoutwardly from the frame side 17 beneath the ring shaped face area 85.It will be noted that the under surface of the upper yoke 90 and theupper surface of the lower yoke 91 are slightly concave to fit thecontour of the inlet and outlet fittings. The upper yoke 90 engages theupper surface of the air outlet fitting 59 or the upper surface 70 ofthe outlet fitting 69 while the yoke 91 engages the under surface of thering shaped connecting portion 49 of the inlet fittings 45 or 46. Theyokes 90 and 91 hold the inlet and outlet fittings sealed to the valvehousing, and holds the valve housings in a vertical upright position.

The connecting rod or bar 24 acts to connect a pair of similar disc-likepistons 94 and 94A which are reciprocable in the cylinders 26 and 26A.The connecting rod 24 is shaped as is best indicated in FIG. 8 of thedrawings. The connecting rod includes a center portion 95 which isconnected along opposite edges to parallel right angularly extendingpanels 96 which define a channel of rectangular section designed toaccommodate the eccentric bearing 23. The edges of the panels 96opposite those connected to the center panel 95 are connected to panelportions 97 which are on a common plane. The panels 97 terminate inpairs of vertically spaced right angularly extending fingers 99 whichare designed for connection with the pistons.

As indicated in FIG. 7 as well as FIG. 4, each piston such as 94 isprovided with a boss 100 projecting in an axial direction from a surfacethereof. The boss 100 is provided with grooves 101 in the upper andlower surfaces thereof adjoining the piston surface, the bases of thegrooves 101 being parallel and being spaced to accommodate the fingers99. Each boss is provided with a flat side 102 which bears againstapanel portion 97 of the connecting rod 24. As will be noted, the pistonssuch as 94 are readily removable from the connecting rod 24 and may beremoved and cleaned whenever desired. The pistons 94 are provided with aperipheral groove 104 to accommodate a sealing ring 105, as indicated inFIGS. 7 and 11 of the drawings. A notch 105 is provided communicatingwith the groove 104 and being of a depth at least equal to the depth ofthe groove 104. This notch 105 provides a means of access to the sealingring 104 so that a portion of the sealing ring may be grasped andstretched outwardly to remove the ring from the groove. This notch 105thus simplifies the task of removing the sealing rings from the pistongrooves 104 and encourages the machine operator to fully disassemble thepistons for cleaning purposes.

The hose 67 is connected to a T connector 106 having a pressure gauge107 extending into one branch of the cross member of the T so that theexisting air pressure may be readily noted. One branch of the T isconnected to stem 109 of the pressure control switch 110 controlling thecurrent to the motor 10. The control switch may be of the type known astype H5 knob and dial adjustment general purpose pressure vacuum controlproduced by the United Electric Controls Company of Watertown, Mass. Thecontrol merely functions to turn on the motor 10 when the air pressurefalls below a predetermined minimum, and to turn off the motor when theair pressure reaches a predetermined maximum.

The operation of the pump is believed obvious from the foregoingdescription. During each cycle of operation, air is drawn into the aircylinder by movement of the piston in one direction, and forced from theair cylinder through the discharge fitting 59 during the compressionstroke of the piston 94A. During each cycle of operation, liquid mix isdrawn into the cylinder 26 by movement of the piston 94, and then isforced upwardly past the check valve 40 as the piston 94 moves in theopposite direction. Air and liquid are mixed and discharged through theconnection 74 and through suitable conduits to the freezer.

By removing the knobs 89 at one end of the unit, the cylinder andattached valve housing as well as the inlet and outlet fittings may bedetached from the corresponding end plate 17. The inlet and outletfittings may be pulled out of the valve housing, and the check valvesare free to drop out of place, and completely disengaging the unit. Allthe parts are accordingly immediately available for cleaning. Thepistons may be disengaged from the piston rods 24, and the sealing rings105 may be easily removed from the pistons 94 to completely disassemblethe unit. Obviously, the sealing rings on the check valves may also bereadily removed, cleaned and replaced.

The operating mechanism is normally concealed and protected by a cover112 which is bent to fit the shape of the ends 17 of the pump frame.

The present apparatus includes a novel feature of overrun variationaccomplished by use of the readily accessible control knob on thepressure control switch 110. A further innovation within this capabilityis that the cylinder/piston design permits a built-in compressionratio/operating pressure characteristic covering a very broad range ofresulting overrun percentages, but still allowing a choice of narrowoperating ranges within each of which a manual range adjustment ispossible.

To understand the meaning of overrun," we start with a pint of liquidmix, the net weight of which may weigh for example, 18.4 ounces. Air isinjected into the mix, and it is frozen. 1f the frozen mixture isreplaced in the one pint container, there will be product left over.With the air added, the volume will increase and the weight per pintwill decrease. The amount of product left over when the pint containeris filled comprises the overrun." This can be accurately determined byweighing the pint of frozen product and comparing this weight to theweight of the liquid mix. The formula for determining the percentage ofoverrun is as follows:

(XY)(100) Y Percent, of overrun:

Where X is the weight of a unit (for example 1 pint) of liquid mix, andY is the weight of 1 pint of the frozen mix. As a specific example, ifthe weight of 1 pint of liquid mix is 18.4 ounces, and the weight of 1pint of frozen product is 9.2 ounces, the formula will be 100% overrunThe following table indicates various percentages of overrun of thefrozen product where the net weight of the liquid mix is 18.4 ounces.

Net weight of Frozen Product k of overrun The present device is uniquein that the percent of overrun may be regulated by varying the maximumair pressure. As the pressure is lowered the percentage of overrundecreases. Thus, while the volume displaced by the piston during eachstroke may remain constant, a broad range of overrun variation isobtainable, because the weight of air delivered is affected by thedischarge pressure as well as by the clearance volume of the cylinderand passages to and from the valves.

It is important to note that the various check valves 40, 42, 43, and 44all are guided by portions which are integral with the valve seats, sothat correct alignment of the valves and their seats is assured. Theupper valves 40 and 43 are slidable within the enlarged diameterportions 33 and 33A of the valve housings 25 and 25A, and the valveseats are formed by the integral connecting portions 39 and 39A. Thelower check valves 42 and 44 are slidable in the cylindrical sleeves 47of the fittings 45 and 46, and the valve seats are formed by theintegral frusto-conical portions 49. Thus, the check valves all slide incylindrical portions which are integral with valve seats.

In accordance with the patent statutes we have described the principlesof construction and operation of our ICE CREAM PUMP, and while we haveendeavored to set forth the best embodiment thereof, we desire to haveit understood that obvious means may be made within the scope of thefollowing claims without departing from the spirit of our invention.

We claim:

1. A readily dismountable pump assembly for use with a pump frame havinga base panel and a pair of right angularly extending frame sidesthereupon, and including a motor secured to said base panel and having amotor shaft on an axis normal to said base panel, said motor extendingfrom said base panel in a direction opposite to the direction of saidframe sides from said base panel, said base panel having an aperturetherethrough intermediate said frame sides aligned with said motor shaftand exposing the same, the pump assembly including:

a pair of cylinders having open ends,

said frame sides having aligned apertures therethrough through whichsaid cylinders extend with the open ends thereof in inner opposedrelation,

means detachably securing said cylinders to said side plates,

pistons slideable in said cylinders,

readily detachable piston rod means connecting said pistons for movementin unison,

valve housings connected to, and communicating with the outer ends ofsaid cylinders, and including readily removable check valves on eitherside of the communication with said cylinders, and

means on said motor shaft detachably engaged with said piston rod meansfor reciprocating said piston rod means upon rotation of said motorshaft.

2. The structure of claim 1 and in which said pistons are disc-likebodies.

3. The structure of claim 2 and including bosses projecting inwardlyfrom the inner surfaces of said disclike bodies, and said piston rodincludes means interengaging with said bosses.

4. The structure of claim 2 and in which said pistons are peripherallygrooved, and including a resilient sealing ring in each of said groovesand projecting therefrom.

5. The structure of claim 4 and in which each said piston includes anotch in the periphery thereof on one side of said groove providingaccess to said resilient sealing ring.

6. The structure of claim 1 and in which said pistons include inwardlyprojecting bosses, and said piston rod includes right angularlyextending means detachably secured to said bosses.

7. The structure of claim 6 and in which the right angularly extendingmeans on said piston rod comprise spaced fingers, and in which saidbosses are grooved to accommodate said fingers.

8. The structure of claim 1 and in which said valve housings arearranged on substantially vertical axes, and in which said check valvesare gravity actuated.

9. The structure of claim 1 and in which said means detachably securingsaid cylinders to said side plates include stud and nut means.

10. The structure of claim 1 and including a pair of yokes extendingoutwardly from opposite sides of said cylinders, and threaded meansforming the means detachably securing said cylinders to said side platesextending through said yokes.

11. The structure of claim 10 and in which said threaded means includestuds projecting in parallel relation outwardly from each said framesides through said yokes, and including threaded knobs on said studs.

12. The structure of claim 1 and in which said piston rod includes acentral offset portion connected to the remainder thereof along parallelsides and said means on said motor shaft comprises a crank supporting acylindrical bearing engageable with said parallel sides.

13. The structure of claim 12 and in which said crank is cylindrical.

14. The structure of claim 12 and in which said piston rod includesright angularly extending end with which said pistons are detachablyengaged.

15. A pump assembly for use with a pump frame having a base panel and apair of parallel right angularly extending frame sides, and including amotor secured to said base panel having a motor shaft on an axis normalto said base panel, said base panel having an aperture aligned with saidmotor shaft and exposing the same, the pump assembly including:

a pair of cylinders having open ends, valve housing connected to otherends of said cylinders and including check valves arranged to controlthe flow of fluid into and out of said cylinders, said parallel framesides having aligned apertures through which said cylinders may extendwith the open ends thereof innermost, pistons in said cylinders, pistonrod means connecting said pistons for movement in unison, means on saidmotor shaft engageable with said piston rod means for reciprocating thesame upon rotation of said motor shaft, inlet and outlet fittings intelescoping relation to said valve housings, and including means on saidparallel frame sides for holding said fittings in telescoping relationto said valve housing when said cylinders are extending through saidaligned apertures. 16. The structure of claim 15 and in which said meanson said frame sides comprise vertically spaced yokes engaging saidfittings.

1. A readily dismountable pump assembly for use with a pump frame havinga base panel and a pair of right angularly extending frame sidesthereupon, and including a motor secured to said base panel and having amotor shaft on an axis normal to said base panel, said motor extendingfrom said base panel in a direction opposite to the direction of saidframe sides from said base panel, said base panel having an aperturetherethrough intermediate said frame sides aligned with said motor shaftand exposing the same, the pump assembly including: a pair of cylindershaving open ends, said frame sides having aligned apertures therethroughthrough which said cylinders extend with the open ends thereof in inneropposed relation, means detachably securing said cylinders to said sideplates, pistons slideable in said cylinders, readily detachable pistonrod means connecting said pistons for movement in unison, valve housingsconnected to, and communicating with the outer ends of said cylinders,and including readily removable check valves on either side of thecommunication with said cylinders, and means on said motor shaftdetachably engaged with said piston rod means for reciprocating saidpiston rod means upon rotation of said motor shaft.
 2. The structure ofclaim 1 and in which said pistons are disc-like bodies.
 3. The structureof claim 2 and including bosses projecting inwardly from the innersurfaces of said disc-like bodies, and said piston rod includes meansinterengaging with said bosses.
 4. The structure of claim 2 and in whichsaid pistons are peripherally grooved, and including a resilient sealingring in each of said grooves and projecting therefrom.
 5. The structureof claim 4 and in which each said piston includes a notch in theperiphery thereof on one side of said groove providing access to saidresilient sealing ring.
 6. The structure of claim 1 and in which saidpistons include inwardly projecting bosses, and said piston rod includesright angularly extending means detachably secured to said bosses. 7.The structure of claim 6 and in which the right angularly extendingmeans on said piston rod comprise spaced fingers, and in which saidbosses are grooved to accommodate said fingers.
 8. The structure ofclaim 1 and in which said valve housings are arranged on substantiallyvertical axes, and in which said check valves are gravity actuated. 9.The structure of claim 1 and in which said means detachably securingsaid cylinders to said side plates include stud and nut means.
 10. Thestructure of claim 1 and including a pair of yokes extending outwardlyfrom opposite sides of said cylinders, and threaded means forming themeans detachably securing said cylinders to said side plates extendingthrough said yokes.
 11. The structure of claim 10 and in which saidthreaded means include studs projecting in parallel relation outwardlyfrom each said frame sides through said yokes, and including threadedknobs on said studs.
 12. The structure of claim 1 and in which saidpiston rod includes a central offset portion connected to the remainderthereof along parallel sides and said means on said motor shaftcomprises a crank supporting a cylindrical bearing engageable with saidparallel sides.
 13. The structure of claim 12 and in which said crank iscylindrical.
 14. The structure of claim 12 and in which said piston rodincludes right angularly extending end with which said pistons aredetachably engaged.
 15. A pump asSembly for use with a pump frame havinga base panel and a pair of parallel right angularly extending framesides, and including a motor secured to said base panel having a motorshaft on an axis normal to said base panel, said base panel having anaperture aligned with said motor shaft and exposing the same, the pumpassembly including: a pair of cylinders having open ends, valve housingconnected to other ends of said cylinders and including check valvesarranged to control the flow of fluid into and out of said cylinders,said parallel frame sides having aligned apertures through which saidcylinders may extend with the open ends thereof innermost, pistons insaid cylinders, piston rod means connecting said pistons for movement inunison, means on said motor shaft engageable with said piston rod meansfor reciprocating the same upon rotation of said motor shaft, inlet andoutlet fittings in telescoping relation to said valve housings, andincluding means on said parallel frame sides for holding said fittingsin telescoping relation to said valve housing when said cylinders areextending through said aligned apertures.
 16. The structure of claim 15and in which said means on said frame sides comprise vertically spacedyokes engaging said fittings.